Hi @Planetschmanet, thank you for posting and bringing this to our attention.
Apologies for your poor experience! If you wouldn't mind just clarifying a few bits of information to help us diagnose the issue:
-Is the phone showing low/no signal when the calls are cutting out?
-Does this happen both indoors, and outside?
-Which network is the phone showing as connected to?
-Do you have an alternative handset you can test the sim in?
It may be worth doing a reboot on the handset, as this will help reset the connection to the local mast!
Hopefully your replacement arrives ASAP to see if this also resolves the issue.
All the best.
Molly